gecko-dev/layout/style/StyleSetHandle.h
Bobby Holley 3836b7c35b Bug 1258017 - Redesign and simplify rule tree GC. r=dbaron
The basic idea here is as follows:
* Rule nodes are reference-counted, but releasing them adds them to a linked
  list rather than freeing them. This allows for the reuse that motivated the
  original GC scheme.
* We get rid of the marking, and instead rely on the reference count.
* Sweeping no longer requires a complicated traversal. We just pop items
  off the free list until it's empty. When a child is destroyed, its parent
  may go onto the free list.
* We remove special handling for the root node, and use a regular reference-counted
  edge from the style set.
* The free list automatically asserts that it's empty (meaning all nodes have been
  freed) in its destructor, which runs when the style set is destroyed.
* We get rid of the list of style context roots on the style set. We still need
  a count though, because of the HasCachedStyleData check.
2016-03-28 08:59:22 -07:00

216 lines
7.6 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_StyleSetHandle_h
#define mozilla_StyleSetHandle_h
#include "mozilla/EventStates.h"
#include "mozilla/RefPtr.h"
#include "mozilla/SheetType.h"
#include "mozilla/StyleBackendType.h"
#include "mozilla/StyleSheetHandle.h"
#include "nsChangeHint.h"
#include "nsCSSPseudoElements.h"
#include "nsTArray.h"
namespace mozilla {
class CSSStyleSheet;
class ServoStyleSet;
namespace dom {
class Element;
} // namespace dom
} // namespace mozilla
class nsIAtom;
class nsIDocument;
class nsStyleContext;
class nsStyleSet;
class nsPresContext;
struct TreeMatchContext;
namespace mozilla {
#define SERVO_BIT 0x1
/**
* Smart pointer class that can hold a pointer to either an nsStyleSet
* or a ServoStyleSet.
*/
class StyleSetHandle
{
public:
// We define this Ptr class with a StyleSet API that forwards on to the
// wrapped pointer, rather than putting these methods on StyleSetHandle
// itself, so that we can have StyleSetHandle behave like a smart pointer and
// be dereferenced with operator->.
class Ptr
{
public:
friend class ::mozilla::StyleSetHandle;
bool IsGecko() const { return !IsServo(); }
bool IsServo() const
{
MOZ_ASSERT(mValue, "StyleSetHandle null pointer dereference");
#ifdef MOZ_STYLO
return mValue & SERVO_BIT;
#else
return false;
#endif
}
StyleBackendType BackendType() const
{
return IsGecko() ? StyleBackendType::Gecko :
StyleBackendType::Servo;
}
nsStyleSet* AsGecko()
{
MOZ_ASSERT(IsGecko());
return reinterpret_cast<nsStyleSet*>(mValue);
}
ServoStyleSet* AsServo()
{
MOZ_ASSERT(IsServo());
return reinterpret_cast<ServoStyleSet*>(mValue & ~SERVO_BIT);
}
nsStyleSet* GetAsGecko() { return IsGecko() ? AsGecko() : nullptr; }
ServoStyleSet* GetAsServo() { return IsServo() ? AsServo() : nullptr; }
const nsStyleSet* AsGecko() const
{
return const_cast<Ptr*>(this)->AsGecko();
}
const ServoStyleSet* AsServo() const
{
MOZ_ASSERT(IsServo());
return const_cast<Ptr*>(this)->AsServo();
}
const nsStyleSet* GetAsGecko() const { return IsGecko() ? AsGecko() : nullptr; }
const ServoStyleSet* GetAsServo() const { return IsServo() ? AsServo() : nullptr; }
// These inline methods are defined in StyleSetHandleInlines.h.
inline void Delete();
// Style set interface. These inline methods are defined in
// StyleSetHandleInlines.h and just forward to the underlying
// nsStyleSet or ServoStyleSet. See corresponding comments in
// nsStyleSet.h for descriptions of these methods.
inline void Init(nsPresContext* aPresContext);
inline void BeginShutdown();
inline void Shutdown();
inline bool GetAuthorStyleDisabled() const;
inline nsresult SetAuthorStyleDisabled(bool aStyleDisabled);
inline void BeginUpdate();
inline nsresult EndUpdate();
inline already_AddRefed<nsStyleContext>
ResolveStyleFor(dom::Element* aElement,
nsStyleContext* aParentContext);
inline already_AddRefed<nsStyleContext>
ResolveStyleFor(dom::Element* aElement,
nsStyleContext* aParentContext,
TreeMatchContext& aTreeMatchContext);
inline already_AddRefed<nsStyleContext>
ResolveStyleForNonElement(nsStyleContext* aParentContext);
inline already_AddRefed<nsStyleContext>
ResolvePseudoElementStyle(dom::Element* aParentElement,
mozilla::CSSPseudoElementType aType,
nsStyleContext* aParentContext,
dom::Element* aPseudoElement);
inline already_AddRefed<nsStyleContext>
ResolveAnonymousBoxStyle(nsIAtom* aPseudoTag, nsStyleContext* aParentContext,
uint32_t aFlags = 0);
inline nsresult AppendStyleSheet(SheetType aType, StyleSheetHandle aSheet);
inline nsresult PrependStyleSheet(SheetType aType, StyleSheetHandle aSheet);
inline nsresult RemoveStyleSheet(SheetType aType, StyleSheetHandle aSheet);
inline nsresult ReplaceSheets(SheetType aType,
const nsTArray<StyleSheetHandle::RefPtr>& aNewSheets);
inline nsresult InsertStyleSheetBefore(SheetType aType,
StyleSheetHandle aNewSheet,
StyleSheetHandle aReferenceSheet);
inline int32_t SheetCount(SheetType aType) const;
inline StyleSheetHandle StyleSheetAt(SheetType aType, int32_t aIndex) const;
inline nsresult RemoveDocStyleSheet(StyleSheetHandle aSheet);
inline nsresult AddDocStyleSheet(StyleSheetHandle aSheet, nsIDocument* aDocument);
inline already_AddRefed<nsStyleContext>
ProbePseudoElementStyle(dom::Element* aParentElement,
mozilla::CSSPseudoElementType aType,
nsStyleContext* aParentContext);
inline already_AddRefed<nsStyleContext>
ProbePseudoElementStyle(dom::Element* aParentElement,
mozilla::CSSPseudoElementType aType,
nsStyleContext* aParentContext,
TreeMatchContext& aTreeMatchContext,
dom::Element* aPseudoElement = nullptr);
inline nsRestyleHint HasStateDependentStyle(dom::Element* aElement,
EventStates aStateMask);
inline nsRestyleHint HasStateDependentStyle(
dom::Element* aElement,
mozilla::CSSPseudoElementType aPseudoType,
dom::Element* aPseudoElement,
EventStates aStateMask);
inline void RootStyleContextAdded();
inline void RootStyleContextRemoved();
private:
// Stores a pointer to an nsStyleSet or a ServoStyleSet. The least
// significant bit is 0 for the former, 1 for the latter. This is
// valid as the least significant bit will never be used for a pointer
// value on platforms we care about.
uintptr_t mValue;
};
StyleSetHandle() { mPtr.mValue = 0; }
StyleSetHandle(const StyleSetHandle& aOth) { mPtr.mValue = aOth.mPtr.mValue; }
MOZ_IMPLICIT StyleSetHandle(nsStyleSet* aSet) { *this = aSet; }
MOZ_IMPLICIT StyleSetHandle(ServoStyleSet* aSet) { *this = aSet; }
StyleSetHandle& operator=(nsStyleSet* aStyleSet)
{
MOZ_ASSERT(!(reinterpret_cast<uintptr_t>(aStyleSet) & SERVO_BIT),
"least significant bit shouldn't be set; we use it for state");
mPtr.mValue = reinterpret_cast<uintptr_t>(aStyleSet);
return *this;
}
StyleSetHandle& operator=(ServoStyleSet* aStyleSet)
{
#ifdef MOZ_STYLO
MOZ_ASSERT(!(reinterpret_cast<uintptr_t>(aStyleSet) & SERVO_BIT),
"least significant bit shouldn't be set; we use it for state");
mPtr.mValue =
aStyleSet ? (reinterpret_cast<uintptr_t>(aStyleSet) | SERVO_BIT) : 0;
return *this;
#else
MOZ_CRASH("should not have a ServoStyleSet object when MOZ_STYLO is "
"disabled");
#endif
}
// Make StyleSetHandle usable in boolean contexts.
explicit operator bool() const { return !!mPtr.mValue; }
bool operator!() const { return !mPtr.mValue; }
// Make StyleSetHandle behave like a smart pointer.
Ptr* operator->() { return &mPtr; }
const Ptr* operator->() const { return &mPtr; }
private:
Ptr mPtr;
};
#undef SERVO_BIT
} // namespace mozilla
#endif // mozilla_StyleSetHandle_h